Marty in Mi.
01-22-2005 05:23:22
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Re: HI-TECH COMPRESION QUESTIONS-FOR THOSE WHO KNO in reply to Clarence Barenie, 01-21-2005 19:23:00
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Clarence, I wish you wouldn't ask questions like this. After reading your post, I was forced to put my boots on and go out to my garage and dig up my notes from 1984 when I did a simular experiment with my F-14. I had just put a .125 over-bore kit in and I was getting 23.5 hp. I was pretty much King of the hill in our area at that time in the 3000# class, but on a good track, I couldn't quite spin out before I ran out of power. My 3.125X4.000 bore and stroke netted me with a 122.72 c.i.d. The combustion chamber volume, including head gasket, was 30.68 c.i.d. 122.72 plus 30.68 divided by 30.68 gave me a 5:1 compression ratio. Needless to say, I was not happy with my results, so off came the head and pan, out came the pistons, and on went some half inch tall 3 inch diameter slugs of aluminum. After welding them to the top of the pistons and spending some time on the lathe getting them all pretty close to the same size(looked like a Hemi piston), I ended up losing 12.21 cubic inches of combustion chamber volume. 30.68-12.21=18.47 cid of combustion chamber volume. 122.72 plus 18.47 divided by 18.47=7.64:1 comp. ratio. This netted me with 30.5 hp. at 540.It used to pick up about 3 hp. when you lugged it down to 400 rpm before the slugs,now it picked up just shy of 6 on the dial.I did not have a M&W calculator at the time,and it's too cold to go back out to the garage and get mine this morning,so I can't say for sure what the hp. readings actually were at 400 rpm,but the difference on the track was amazing. I could now spin out in 2nd gear at 3000# and also spin out in low gear at 3500#. By the way, I did not change anything else on the engine. This actually was a descently efficient engine combination,making about .25 hp. per cubic inch. Got to run for now, looks like we got about 6 inches of snow last night,and I've got to put the snow-blower on the mighty Wheel Horse. Marty
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